Questions - Session I

Bert Bolin, Pieter Tans, Thomas Karl

DR. WATSON: The first question is one for Bert Bolin. Why
does it matter if there is a discernible human influence on
global climate?

DR. BOLIN: If there is one at this stage that we can
identify with what man is doing, it is very likely that it is
going to increase. That is after all what we are concerned
about. Still, as I said, we have not yet assessed and quantified
the sensitivity of the climate system to changes of greenhouse
gasses and aerosols very well. But there is a positive relation
that is quite clear, as far as I can judge.

But maybe you aren't concerned about the warmer climate. I
did not address impacts very much.

DR. WATSON: I would add to that. I think it starts to give
us more confidence in elements of our theoretical models, which
do of course predict significant changes in the absence of
climate policies into the future.

I also believe it will fundamentally start to reshape the
political debate internationally, I believe it is going to be
much harder for certain delegates to argue there is no evidence
of a human influence on the climate system.

On a much simpler issue, stratospheric ozone depletion, once
we have established cause and effect between human activities and
stratospheric ozone, it had a major effect on the international
negotiations.

I was asked a question. How do you get politicians with a
short attention span to favor support for long term research and
actions? I'm not sure the problem in the U.S. at the moment is
that they have a problem with long term research. The problem
is, for some of them, they don't believe in these environmental
issues. It isn't so much that you have to study them for the
long term; they have supported rather well research on
stratospheric ozone. They have supported quite well fundamental
basic research in the National Science Foundation.

The problem we face at the moment is that some people who
are rather influential in Congress don't believe global warming
or global change is an environmental issue that we should care
about at all.

As far as long term action, I think we have to convince
people that climate change in the absence of policies is going to
be very serious to both the United States and the rest of the
world, and taking some near term actions will be beneficial to
economic growth and the health of the average American citizen,
let alone citizens around the world. So I don't totally despair
that we can get them to move in the right direction, but it is a
challenge.

To Tom Karl, Skeptics make a lot of the satellite data,
indicating recent cooling. Can you expand on this? You
obviously talked about it in your talk, but do you want to expand
upon this?

DR. KARL: I think it is very important not to be misled by
short records of 10 to 15 years. This has been unfortunate that
at first, satellite records were looked upon as being in conflict
with the surface records, because they showed warming. There was
some notion that the satellite was not looking at the potential
urban effects, so therefore perhaps the warming that we have seen
at the surface was purely due to urbanization.

Indeed, when you compare those satellite measurements with
the weather balloons, they are fairly consistent. The satellites
themselves are not totally perfect. In fact, just last year the
record was revised by about a six-hundredths of a degree Celsius
per decade because of some biases. There is a lot of work that
has gone into those records to try and alleviate biases. The
satellites don't measure the diurnal cycle completely. As the
satellites change, some of them measure some parts of the diurnal
cycle, others measure other parts of the diurnal cycle.

But I do not believe there is a serious inconsistency
between the satellite measurements, the weather balloons and the
surface measurements. One has to be extraordinarily carefully
about looking at a short record and making grand conclusions.

DR. WATSON: Thank you. It is quite clear that over one to
two decades, one can clearly have a natural cooling trend that
would easily offset any projected increase due to anthropogenic
emissions of greenhouse gasses.

For Pieter Tans, what effects could the death or loss of
coral reefs have on the CO2 system?

DR. TANS: It could have a tremendous effect. I did talk
about it. I showed you a titration diagram, and I talked about
bicarbonate and borate and CO2.

There was a lower diagram I didn't talk about, the pH. The
pH of the oceans of course will go down as we add this carbon
dioxide. At a certain point, coral reefs might become
susceptible to solution.

If we manage to burn all the fossil fuel reserves, we might
get into that range. In that case, it would also put a natural
cap on the CO2 increase in the atmosphere, because the addition
of calcium ions to the ocean and would increase of the ocean's
capacity to hold carbon. In that sense, it is good, but of
course, it is an ecological disaster of the first order.

DR. WATSON: A nice soft question for Dr. Bolin. In Madrid,
several strong and particularly informative statements were
edited out of the Working Group One report solely as the result
of objections from non-scientists working in oil ministries in
Saudi Arabia and Kuwait, based on briefs provided by the U.S.
fossil fuel lobbyists. Are you worried about this new
development?

DR. BOLIN: Yes, indeed. I think we have tried in the
scientific community to accommodate different views, maybe a
little too much. We haven't asked adequately for the scientific
justification for some of these objections. It is a natural
trend in a scientific debate, trying to see what kind of
uncertainty we have.

However, it was a very important decision taken. That is,
we did separate this very clearly on one occasion. It will be
in the reports, an explicit statement that Saudi Arabia and
Kuwait did not agree. I think this is very important, because it
should encourage a much more clear distinction on matters of this
kind.

It is not the purpose, I have said a dozen times, of the
IPCC to just try to compromise into a common view, if there are
different views, they should be reported. I hope this is done
more in the future than it has in the past.

With regard to the lobbyists, I note that from now on, or
soon, all lobbyists will have to declare from where they get
their incomes. In that way, it will be much more obvious, not
least in the United States, from where these views stem.

DR. WATSON: I think the answer by Dr. Bolin is very
important. More and more, some of the IPCC plenaries are
becoming negotiating sessions on particular sentences, because
some delegations realize those sentences may be quoted back in
negotiations on policy formulation under the Conference of
Parties. I believe the approach taken by Bert Bolin and John
Horton in one instance of isolating those two particular
countries and putting them as a footnote needs to be done far
more, and we can't keep going towards the lowest common
denominator in all of our debates. A country that has a problem,
or two or three countries that have a problem with a particular
sentence should be willing to be noted in the footnotes as having
a problem. I think that is the approach that will be taken far
more in the future, rather than negotiating for hours to a lowest
common denominator sentence that absolutely everybody can buy
into.

DR.WATSON: A question for Tom Karl. Given we are seeing a
signal of the greenhouse effect, how much of that signal can be
attributed to anthropogenic activities? A nice easy one.

DR. KARL: The unfortunately part about that question is the
whole basis of what we are trying to do. That is, it is
impossible for us to say exactly how much of the signal that we
see is due to any specific forcing. That is why we spend a lot
of time on trying to look at estimates of natural variability and
trying to detect changes that go above that estimated natural
variability.

But what it does speak to is the fact that as climate does
vary and change, and we see evidence for changes that exceed our
estimates of natural variability, we then are confident that what
we are seeing is in agreement with our expectations.

Another way to look at this is that climate could be varying
naturally in a way that would enhance our ability to see
particular climate variation or variability, or give us a false
sense. That is, the globe might be warming naturally, just
because the globe has internal variability in its warming, or it
could be cooling, just because it has some internal natural
variability.

So the question goes both ways. But our best estimates of
natural variability would suggest that the signals that we are
seeing are merging above and beyond that noise.

DR. WATSON: A question for Pieter Tans. What if we don't
want carbon dioxide to increase to more than one thousand parts
per million? For example, what if we want to keep CO2 from
exceeding 450, what is the implication for burning all the fossil
fuels?

DR. TANS: It would be Draconian. I showed the real long
term effect of it. If we want to keep CO2 below 450 ppm
permanently, I guess we would have to stop just about today,
almost.

DR. BOLIN: There is in the summary for Working Group One
very clear statements that if you wish to stabilize at 450, you
mustn't emit during the next 110 years more than 600 gigaton,
which is just about the average emission during the next century
as the present emissions. But we also need from about 2100
onwards to get very much below this. So you can peak during the
next few decades, but then you must get down. Whether that is
possible or not remains for others to answer.

DR. WATSON: Yes, if you were to stabilize at today's global
emissions, you would not stabilize concentrations. They would
continue to rise up for many centuries, passing 500 parts per
million by the end of the next century, going past 550, 560
within two centuries, and they would continue to go up, meaning
that you would have to eventually reduce the emissions back to
something like three gigatons of carbon per year. So even
stabilization around 450 to 550 would mean very significant
cutbacks in the total amount of CO2.

DR. TANS: Then after that period you would have to emit
even less. Cutting back to three gigatons is not going to do it.
You have to go back to zero.

DR. WATSON: A question for Bert Bolin. What future role do
you foresee for the IPCC in terms of assessments vis-a-vis the
role of SUBTA under the conference of parties, for those of you
who don't what SUBTA is.

DR. BOLIN: IPCC I think has established its credibility in
the scientific community. That has taken five years, I would
say. SUBTA today has no credibility within the scientific
community, naturally so. It is by and large a political
committee. It is an open-ended committee where anyone can be
represented. Therefore, it is not likely that it can achieve a
scientific credibility of the kind that IPCC has.

That may be, but why change when there is something that
works reasonably well. That is my question. The IPCC will
continue. About every five years is what, not I, but scientists
are others, think is a plausible interval between such major
assessments. But in between, there is a need to get in much more
of a dialogue with the subsidiary bodies of the convention in
order to transfer information. But in doing so, as sharply as
possible maintain the scientific integrity of the IPCC.

DR. WATSON: There is a question here for Tom Karl. Do we
really have a long enough time series of ENSO data to say that it
has been behaving in an unusual manner? How well defined is the
normal ENSO cycle? I can comment that in the policy makers'
summary, we say that since 1989, the persistence from '89 through
'94 is unusual in the last 120 years. Maybe you would like to
amplify.

DR. KARL: When we say unusual, we are saying that word in
terms of both the direct observation we have and some evidence
from coral records that also suggests that the variability that
we have seen recently would still be considered unusual,
inferentially suggesting that there are some very interesting
things going on with ENSO recently.

DR. WATSON: There is a question here for Bert Bolin. In
Rome, should calls for striking certain chapters of the Working
Group Three Report on definition of the value of a statistical
life arise, how will they be handled? For example, will you
refuse to open all the reports or reflect this in the synthesis
report?

DR. BOLIN: The working groups adopt the Summary for Policy
Makers. When it comes up in the IPCC plenary, we must uphold
that kind of a procedure. It is very essential. Otherwise,
things start to just disintegrate.

Now, anyone can request that something be added to the
minutes of the meeting in Rome. That of course will have to be
accepted. But it is also important to clarify that acceptance
does not mean that you agree with what is written there. The
thing is, it is acceptance that this is a fair summary of what
the scientific community has done. If politicians don't agree
with that, that is their business. That is reasonably well
reflected in the kind of Policy Makers' Summary that Working
Group One was able to agree on, which is implicitly some
criticism of the underlying chapter, in that it has been too
stringently based on rather formalistic assumptions with regard
to how you assess costs and benefits.

Procedures as we have them must be upheld very stringently.

DR. WATSON: A question to no one in particular. What is
the global warming potential of water vapor? The answer is, IPCC
has not calculated one. There is another question that is
somewhat linked. I'll phrase it. Are carbon dioxide and water
vapor included in GCMs for calculating global temperature? The
answer is quite clearly, the way we drive the GCMs or the simple
box Upwellan models of climate is by changing the emissions of
gasses such as carbon dioxide, methane and CFCs and nitrous oxide
into the atmosphere, and looking at the response. None of the
GCMs assume a change in emissions of water vapor, but water vapor
should respond to changes in the temperature structure of the
earth's atmosphere. Hence, water vapor, both in the lower and
upper troposphere, is a feedback mechanism to the perturbation or
the change in radiated forcing of greenhouse gasses. Hence, we
use water vapor as a response to forcing, not as a forcing
mechanism directly in its own right.

So clearly, the GCMs do take into account changes in both
carbon dioxide and water vapor, and their influence on the
radiated balance both in the troposphere and the stratosphere,
both are quite important.

DR.WATSON: A question for Tom Karl. Why do you suppose
there is no evidence of increased incidence of extreme drought in
the warm season within the USA?

DR. KARL: I think there are two reasons that that has not
occurred. One is, the 1930s drought event in the U.S. was such a
spectacular event, it may indeed be very ill-advised to focus on
looking at changes in drought frequencies in the U.S. as being a
greenhouse signal, simply because it would take a long time for
that type of event to be smeared out in the record.

Secondly, we have found an increase in cloud cover over the
U.S. Part of this could perhaps be due to the El Niño southern
oscillation event. Part of it also may be related to natural
variability. Another part could be related to indirect effects
of sulfate aerosols. All these are possibilities. But
nonetheless, the addition of cloud cover does tend to make the
maximum temperature less than what it might otherwise have been.
Therefore, we don't see a tremendous rise in the increase of
extreme events associated with drought.

If you look at the records, there is a slight indication of
a greater portion of the U.S. having more extreme and severe
droughts, but it is very slight. We would be splitting hairs to
say it is anything other than no change at all. But again, the
drought event in the '30s, that really stands out.

DR. WATSON: A question for Bert Bolin. Your correlation
coefficient was 0.3 for modeled and observed delta temperature.
What is the statistically significance of that number, and is the
correlation convincing to the eye?

DR. BOLIN: Yes, it is convincing to the eye. You can look
up the picture in Chapter 8 of Working Group One, where this is
clearly brought home. It is much better that you look at that
than let me explain it to you, because those writing that are
much more knowledgeable than I am. But it is a clear indication
that the correlation between model and observed patterns has
increased with time over the last 20 or 30 years.

It is not an exact agreement in any way, because of the
natural variability, essentially. But there is an increasing
resemblance between these two patterns in the course of time.

DR. WATSON: In fact, if you look at the diagram shown by
both Bert Bolin and Tom Karl, the model which had CO2 only,
and
look at the pattern of the CO2 only and the observations, you
have a negative correlation that is getting worse with time; it
just goes down. If you then bring in the fact that there has
also been a change of sulfate aerosols and other aerosols and a
depletion of stratospheric ozone, you find a positive correlation
between the observations and the theoretical models increasing
with time.

So I think it is rather convincing. We saw some of this
information in Madrid. It is obviously in the assessment
documents. It is rather convincing, even to the eye. So I think
the point Tom Karl made is the most important. Any one piece of
information could be challenged. It is the ensemble of all of
the information, the agreement of the global mean annual
temperature over the last hundred years with the theoretical
models, that take into account both greenhouse gasses and
aerosols. It is the latitudinal and longitudinal distribution
and the vertical distribution, when you take all of that ensemble
into account, then it starts to become quite convincing that you
can make this cause and effect statement, as we have in Working
Group One.